Joint timing recovery and decoding algorithms for non-binary LDPC coded systems

In this paper, we present two joint timing recovery and decoding algorithms for non-binary low-density parity-check (LDPC) coded systems. To estimate the timing offset, the first algorithm utilizes the percentage of the satisfied check nodes (SCNs), while the second algorithm utilizes the soft decision metrics (SDMs). Both SCNs and SDMs are fed back from the LDPC decoder, which can be implemented by either the well-known q-ary sum-product algorithm (QSPA) or other low complexity algorithms, such as the X-EMS algorithms. Simulation results show that the proposed algorithms suffer from a little performance degradation compared with the perfect timing system. Simulation results also show that X-EMS algorithms aided by the timing recovery algorithm using SDMs outperform QSPA aided by the timing recovery algorithm using SCNs, but with a much lower complexity. This implies that the performance is mainly affected by the timing recovery algorithms.